1. Field of the Invention
This invention is directed to a device which is, in general, useful in a substantially weightless condition or environment and, more particularly, a device which is useful by workers in such an environment, such as astronauts or aquanauts.
2. Prior Art
With the advent of space travel and exploration, many unique and previously unexpected situations and problems have developed. One of the significant problems is that, in a weightless (or substantially weightless) condition, certain working manipulations and movements are difficult, if not impossible, to perform compared to the same activity with earth's gravity present. For example, many activities which use primarily the arms and upper torso in a gravity condition, are not readily performed in a weightless condition inasmuch as the legs and lower torso provide no stabilizing effect or reactive surface or friction. That is, with gravity, the legs and/or feet act to provide the pelvis with a stable "platform" for a motion and action of the back, torso and arms interacting as a unit to generate working movements. Notably, these types of movements do not require the leg-flexing forces but do require the related traction imparted by the feet against the "floor". However, in the weightless or near-weightless environments of space or neutral-buoyancy underwater, the legs and feet combination have no such platform to attach to, react against or derive tractive friction from. Such surfaces to attach to, react against and give traction to the soles of the feet must be, at best, artificially supplied at every pre-determined worksite and related orientation(s), if, both hands are required to perform the work. Otherwise, one hand must grip a reactive/retaining structure to react the workloads and hold position. The requirement, to provide an artificial "piece-of-floor", leg-length removed from the equipment/surfaces man must manipulate within the premium pressurized volume of the space-craft (with its multiple functions) imposes severe design and volume use limitations on the interior spaces and surfaces.
Current practice (in earth gravity) dedicates flat "floor" surfaces in these volumes to be used with suction-cup platforms attached to the shoes. This then dictates that all work station surfaces must be facets of the surrounding wall perimeter of the pressurized volumes, and be a nominal leg length distance from the established "floor" surface. This practice is further compromised in volumetric requirements by the recent knowledge that the body's muscle structure renders the upright/vertical posture fatiguing, except for brief intervals, in the weightless environments. The neutral/comfort configuration/position of the body being near that in a chaise lounge with a head-elevating pillow.
The body accommodating envelope is no longer a convex oval tube but is a profile both convex and concave, with the foot element no longer at right angles (obtuse) to the lower leg. This body configuration further complicates the interior volumes and "floor" surfaces of the space vehicles and the functions these volumes enclose and define. There are provided hand holds/rails at intervals in the interior volumes for temporary positioning and moving about, but their use for work station positioning leaves only one hand free until the orientation is assumed to attach the feet to the "floor". However, this often is not achievable in the premium volumes.
A multiplicity of hand holds/rails in the manner of a "jungle gym" inside the limited volume is clearly an undesirable intrusion, so these aids (hand holds) are discretely and widely spaced for this reason and also because of the penalties of weight and structural requirements.
For the condition of "outside" the space vehicle's pressurized (atmospheric) volume, the suction-cup shoes will not function in the vacuum of space. Also, the restraint/positioning problem for working, pressure-suited in weightlessness is further complicated by the restricted movement of, notably the legs, and, to a lesser degree, the arms, as imposed by the pressure suit. Indeed, the astronaut must do muscle work against the suit to move out of the neutral position designed into the suit. Significantly, knee and leg-flexing are severely limited and demand muscle work by the astronaut to move to these out-of-neutral positions and to sustain them only briefly. This is notably true of the leg flexings. The useful and remaining suit movements for working manipulations are those of the torso and the arms in combination. This combination's effectiveness is, of course, prime because of the prehensile feature of the hands and their remaining sense of touch, with the important aspect that most of these manipulations can be within the astronaut's vision.
Current practice is to insert the pressure-suited astronaut's feet in a prepositioned "piece-of-floor" containing rigid, toe and heel traps which can be entered and exited by the gross positioning and movements of the pressure-suited astronaut's boots. This "piece-of'floor", foot-trap must either be pre-positioned or designed into the "outside" site, or the foot-trap must be transported by the pressure-suited astronaut to the site and set up in a discrete orientation. However, the astronaut's prime means of locomotion near the space vehicle structure is hand-over-hand via hand holds/rails or via pre-strung tether lines. Therefore, anything he takes with him must be attached to him or be moved by him along a "slide-wife" for origin to destination, with the astronaut supplying the starting force, the controlled motion and finally the "braking force". Clearly, "piece-of-floor", foot-trap structures may not be provided within the aerodynamic envelope, external to the space vehicle, and at most, accessable attachments, below the surfaces, to which foot-trap structures may be attached, after transport to the site can only be achieved by significant penalties and energy of the pressure-suited astronaut's work schedules.
"Piece-of-floor" positioning requires a one-handed operation and hand holds in working proximity. If positioning adjustment is required in use, the astronaut must get out of the foot-trap, move "down" to the trap mount via hand holds to where he can reach it and observe it. Then he must reposition it with one hand, guess at its new position, climb "up" and re-enter the foot-trap again before work may be continued.
The alternatives of providing reacting "floor" surfaces (foot-traps) at every anticipated work site "outside" the space vehicle, or even inside the pressure volumes, are nearly impossible to very exacting, in their design penalties and certainly do not lend to any improvisation that might become necessary. Present methods and arrangements are inflexible, awkward, time consuming and necessarily expensive to use.
Clearly, an ideal solution is to provide a fully portable, readily variable, generally and rapidly adaptable positioning system expoiting the structure and configurations of existing and extendable hand hold/rail systems now necessary for hand-over-hand mobility both inside and "outside" the space vehicles. Such a system may well be adaptable to expliot the modular open-truss structures of large scale as currently envisioned for future space structures in near-earth orbits.